Method and apparatus for selecting MBMS radio bearer type

ABSTRACT

A method and apparatus for selecting a radio bearer type for providing a service to a plurality of mobile terminals according to a count of mobile terminals obtained through responses to a service response request message from a network is provided. An MBMS radio bearer type is selected according to a count that includes RRC-connected mobile terminals that still need to establish a connection in order to receive an MBMS such that the radio bearer type established is sufficient to provide the MBMS to all mobile terminals desiring to receive the service.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 12/336,383, entitled “METHOD AND APPARATUS FOR SELECTING MBMSRADIO BEARER TYPE,” filed on Dec. 16, 2008, and which is incorporated byreference herein. U.S. patent application Ser. No. 12/336,383 is acontinuation application of U.S. patent application Ser. No. 10/924,093,filed on Aug. 19, 2004, now U.S. Pat. No. 7,477,619, and which is hereinincorporated by reference, and claims the benefit of Korean ApplicationNo. 10-2003-057388 filed on Aug. 19, 2003, which is hereby incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for providing aservice, such as a multimedia broadcast/multicast service (MBMS), in auniversal mobile telecommunications system (UMTS), and moreparticularly, to a method and apparatus for selecting a radio bearertype according to a count of mobile terminals obtained through responsesto a service response request message from a network.

2. Discussion of the Related Art

The universal mobile telecommunications system (UMTS) is athird-generation mobile communications system evolving from the globalsystem for mobile communications system, which is the European standard.The UMTS is aimed at providing enhanced mobile communications servicesbased on the GSM core network and wideband code-division multiple-accesstechnologies.

A conventional UMTS network structure 1 is illustrated in FIG. 1. Onemobile terminal 2, or user equipment (UE), is connected to a corenetwork 4 through a UMTS terrestrial radio access network (UTRAN) 6. TheUTRAN 6 configures, maintains, and manages a radio access bearer forcommunications between the UE 2 and core network 4 to meet end-to-endquality-of-service requirements.

The UTRAN 6 consists of at least one radio network subsystem 8,including one RNC 10 acting as an access point to the core network, andat least one Node B 12 managed by a corresponding RNC. The RNCs 10 arelogically classified as controlling RNCs, which allocate and managecommon radio resources for a plurality of UEs 2 of a cell, and servingRNCs, which allocate and manage dedicated radio resources for a specificUE of a cell. Each Node B 12 manages at least one cell.

The core 4 network may be divided according to the type of serviceprovided, namely, a circuit-switched (CS) domain and a packet-switched(PS) domain. The CS domain includes a mobile switching center (MSC) 14acting as an access point to the UTRAN 6 and a gateway mobile switchingcenter (GMSC) 16 acting as an access point to an external network. ThePS domain includes a serving GPRS support node (SGSN) 18 acting as anaccess point to the UTRAN 6 and a gateway GPRS support node (GGSN) 20acting as an access point to the external network.

In the CS domain, the core network's 4 access point is the MSC 14 via anlu-CS interface. In the PS domain, the core network's 4 access point isthe SGSN 18 via an lu-PS interface. A visitor location register (VLR) 22and a home location register (HLR) 24 manage user registrationinformation.

The air interface (Uu) between the UE 2 and the UTRAN 6 includes a radioresource control (RRC) layer (not shown) for the establishment,reconfiguration, and release of radio bearers, for example a serviceproviding data transfer between the UE and an RNC 10 of the UTRAN. A UE2 is said to be in the RRC-connected mode when the RRC layer of a UE andthe RRC layer of a corresponding RNC 10 are connected, thereby providingfor bi-directional transfer of RRC messages. If there is no RRCconnection, the UE 2 is said to be in the RRC-idle mode.

The serving RNC 10 of an RRC-connected UE 2 recognizes and manages theUE by cells. An RRC-idle UE 2, on the other hand, cannot be recognizedby cells and can be considered invisible to the RNC 10. Therefore, theMSC 14 or SGSN 18 of the core network 4 manages RRC-idle UEs 2 usinglarger areas, such as location units or routing area units.

Upon power-up, a UE 2 is in the RRC-idle mode by default. Whennecessary, an RRC-idle UE 2 transitions to the RRC-connected modethrough an RRC connection procedure.

An RRC connection is established, for example, when uplink data transferis needed to make a call or to respond to a paging message from the RNC10. The RRC connection connects the UE 2 to the RNC 10 of the UTRAN 6.However, in order to receive a service, for example MBMS, the UE must beconnected to the core network 4 (MSC 14 or SGSN 18). Connection of theUE 2 to the core network 4 for control of the service is achieved by a“signaling connection,” either a CS connection or PS connectionaccording to the type of service.

A CS connection, which is established between the UE 2 and MSC 14,consists of an RRC connection and an lu-CS connection. When there is aCS connection, the UE 2 is said to be in the circuit mobility management(CMM) connected, or CMM-connected, mode. When there is no suchconnection, the UE 2 is said to be in the CMM-idle mode.

A PS connection, which is established between the UE 2 and SGSN 18,consists of an RRC connection and an lu-PS connection. When there is aPS connection, the UE 2 is said to be in the packet mobility management(PMM) connected, or PMM-connected, mode. When there is no suchconnection, the UE 2 is said to be in the PMM-idle mode.

One UE 2 may have two signaling connections, for example both a CSconnection and a PS connection, but only one RRC connection. AnRRC-connected UE 2 may have no signaling connection, whereby the UE ismanaged by the RNC 10 only and cannot receive services.

To join a specific MBMS, both an RRC connection and an lu-PS connection,or a PS connection, is required through which a UE 2 is connected to theSGSN 18. An MBMS-joined UE 2 remains in the RRC-connected mode bymaintaining the PS connection. Upon termination of the service, the UE 2transitions to the RRC-idle mode by severing the PS connection.

When MBMS data transfer is eminent and a UE 2 is standing by, forexample intending to receive data of the MBMS, the SGSN 18 sends a“session start” message to the RNC 10. The RNC 10 transmits an MBMSnotification message to the UE 2 at least once before the MBMS data istransferred.

The MBMS notification message is transmitted via a combination of commonlogical and transport channels. At the time of MBMS notification, theRNC 10 recognizes, or counts, the number of UEs 2 joining the MBMSwithin a cell. The counted number of UEs 2 determines whether a radiobearer will be established for providing a specific MBMS, and if so,whether the established radio bearer will be a point-to-multipoint(p-t-m) type or a point-to-point (p-t-p) type. Proper establishment of aradio bearer ensures efficient utilization of radio resources.

FIG. 2 illustrates a conventional connection of a plurality of UEs 2 toa core network 4 providing an MBMS. The RNC 10 first receivesinformation from the SGSN 18 to determine the number of UEs 2 intendingto receive the MBMS. Recognizing the presence of UEs 2 that join theMBMS and remain in the RRC-connected mode due to another service, theSGSN 18 provides the RNC 10 with information regarding PMM-connected UEs2.

Specifically, the SGSN 18 provides “initial” UE 2 identificationinformation, such as an intrinsic identifier or ID assigned to each UE,and the MBMS identification, or service ID information, of the specificservice that the UE is joining. The RNC 10 stores the initial UE IDs ofthe UEs 2 joining the MBMS and thereby counts the number ofRRC-connected UEs among a plurality of UEs joining the MBMS.

The initial UE ID enables the identification of a UE 2 regardless of itsRRC connection status, thereby enabling identification of UEs by a corenetwork 4 entity such as the MSC 14 or SGSN 18. The initial UE ID may bean international mobile subscriber identity (IMSI) enabling asubscriber's identification worldwide, a temporary mobile subscriberidentity (TMSI) allocated by the MSC 14 to a UE 2 having a CS connectionfor security of the IMSI, or a packet TMSI allocated by the SGSN 18 to aUE having a PS connection.

Since RRC-idle UEs 2 are invisible to the SGSN 18, a UE havingtransitioned to the RRC-idle mode after joining the MBMS cannot becounted by the RNC 10 in the same manner as an RRC-connected UE. Inorder to count RRC-idle UEs 2, the RNC 10 receives an RRC-connectionrequest message from each RRC-idle UE receiving an MBMS response requestmessage via a combination of common logical and transport channels. TheRRC-connection request message is transmitted by a UE to inform the RNC10 of its presence using a combination of common logical and transportchannels. The RRC-connection request message includes the service ID ofthe MBMS that the UE 2 intends to receive.

The RNC 10 adds the number of RRC-idle UEs 2 to the number ofRRC-connected UEs, which is a number included in the PMM-connected UEinformation received from the SGSN 18, in order to determine the totalnumber of UEs intending to receive the MBMS in each cell. The RNC 10compares the total to a threshold. If the number of UEs 2 intending toreceive the MBMS in a cell is less than the threshold, the RNC 10establishes a p-t-p MBMS radio bearer. If the number of UEs 2 intendingto receive the MBMS in a cell is greater than the threshold, the RNC 10establishes a p-t-m MBMS radio bearer. No MBMS radio bearer isestablished for the cell if there is no UE 2 intending to receive theservice.

After determining the appropriate MBMS radio bearer, the RNC 10 informsthe UEs 2 accordingly. If a p-t-p MBMS radio bearer is established for aspecific MBMS, each UE 2 intending to receive the service transitions tothe RRC-connected mode. On the other hand, if a p-t-m MBMS radio beareris established, it is unnecessary for all the UEs 2 to remain in theRRC-connected mode since MBMS data reception by RRC-idle UEs is enabledwhen a p-t-m radio bearer is established.

The RNC 10 informs the SGSN 18 of the established MBMS radio bearer. Intransmitting MBMS data via the established MBMS radio bearer, the SGSN18 first transmits the session start message, followed after a timeinterval by the MBMS data. The time interval is sufficient for the RNC10, in response to the session start message, to send an MBMSnotification to the UEs 2, to count the UEs, and to determine the MBMSradio bearer.

In performing the MBMS counting function to determine the appropriateMBMS radio bearer, an RNC 10 adopting the conventional method receivesinformation regarding RRC-connected UEs. The number of RRC-idle UEs 2 isdetermined by the number of UEs that respond to an MBMS response requestmessage with an RRC-connection request message.

However, not all RRC-idle UEs 2 in a cell intending to receive the MBMSneed to transmit an RRC-connection request message. The conventionalmethod cannot determine the number of UEs 2 in the RRC-connected modeand PMM-idle mode.

If a CS connection is established, for example for carrying out a voicecommunication function, by an MBMS-joined UE2 having transitioned to theRRC-idle mode to stand by for MBMS notification, an RRC connectionexists but without a PS connection. In the conventional method, theRRC-connected but PMM-idle UE 2 is omitted from the RNC's 10 count sincethe SGSN 18 is unable to inform the RNC of the UE's presence.

An incorrect count of UEs 2 may be a serious problem if there are veryfew RRC-idle UEs among those joining an MBMS in a cell. A particularproblem may occur if the number of RRC-idle UEs 2 is below the thresholdfor triggering a p-t-m radio bearer.

For example, if only one among a relatively large number of UEs 2joining a specific MBMS within a cell stands by for MBMS notification inthe RRC-idle mode and all others enter the RRC-connected mode toestablish a CS connection, the RNC 10 is unable to recognize themajority of UEs since they are in the RRC-connected and PMM-idle mode.Since the RNC 10 counts only one UE 2 intending to receive the MBMS withthe conventional method, a p-t-p radio bearer is established. A p-t-pradio bearer is an insufficient resource for the majority of the UEs 2in the ceil to receive the MBMS. In an extreme case, when every UE 2 ofa cell is in the RRC-connected and PMM-idle mode, the RNC 10 would stopMBMS data transfer altogether since no UEs 2 intending to receive theMBMS would be counted using the conventional method.

Therefore, there is a need for a method and apparatus for accuratelycounting the number of mobile terminals in a cell that need to establishan RRC-connection to receive a specific service in order to properlydetermine the appropriate radio bearer needed. The present inventionaddresses these and other needs.

SUMMARY OF THE INVENTION

The present invention is directed to a method and apparatus forselecting a radio bearer type for providing a service to a plurality ofmobile terminals according to a count of mobile terminals obtainedthrough responses to a service response request message from a network.Specifically, the invention is directed to a method and apparatus thatfacilitates selecting an MBMS radio bearer type according to a countthat includes RRC-connected mobile terminals that still need toestablish a connection in order to receive the service such that theradio bearer type established is sufficient to provide the service toall mobile terminals desiring to receive the service.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the presentinvention is embodied in a method and apparatus that providesinformation to a network to facilitate determination of the appropriateradio bearer type to provide a service to a plurality of mobileterminals by counting those mobile terminals that either have noexisting connection with the network or have an existing connection withthe network that is not sufficient to receive a desired service, whileexcluding from the count those mobile terminals that have an existingconnection with the network that is sufficient to receive the service.Specifically, mobile terminals that are either in the RRC-idle state orin the RRC-connected state but the PMM-idle state provide a response toa response request message from a network that facilitates an accuratecount of those mobile terminals desiring to receive apoint-to-multipoint service in a mobile communication system.

In one aspect of the present invention, a method is provided forreceiving a service in a mobile terminal. The method includes receivinga response request message associated with the service from a networkand transmitting to the network either a connection request message or anotification response message. A connection request message istransmitted if no connection for exchanging control data with thenetwork already exists. A notification response message is transmittedif a connection for exchanging control data with the network alreadyexists. The network counts the number of connection request messages andnotification response messages received to determine the appropriateradio bearer to establish.

When determining whether to transmit a connection request message or anotification response message, a mobile terminal is considered to be inan RRC-idle state if no connection for exchanging control data with thenetwork exists and considered to be in an RRC-connected state if aconnection for exchanging control data with the network already exists,regardless of whether the connection is sufficient to receive theservice. Therefore, mobile terminals desiring to receive the servicethat have no existing connection with the network will transmit aconnection request message while mobile terminals desiring to receivethe service that have an existing connection with the network willtransmit a notification response message. Since all mobile terminalsdesiring to receive the service will provide a response, an accuratecount of mobile terminals is facilitated.

It is contemplated that the service may be a point-to-multipointservice. Preferably, the mobile terminal has joined the service in amobile telecommunication system.

It is contemplated that the response request message is received via acombination of common logical and common transport channels, acombination of dedicated logical and common transport channels, or acombination of dedicated logical and dedicated transport channels. It isfurther contemplated that the combination of channels is based on anoperational state of the mobile terminal.

Preferably, the response request message is received via a combinationof common logical and common transport channels when the mobile terminalis in the CELL_PCH state or the URA_PCH state. Preferably, the responserequest message is received via a combination of common logical andcommon transport channels or a combination of dedicated logical andcommon transport channels when the mobile terminal is in the CELL_FACHstate. Preferably, the response request message is received acombination of common logical and common transport channels, acombination of dedicated logical and common transport channels, or acombination of dedicated logical and dedicated transport channels whenthe mobile terminal is in the CELL_DCH state.

It is contemplated that the notification response message is transmittedvia a combination of common logical and common transport channels, acombination of dedicated logical and common transport channels, or acombination of dedicated logical and dedicated transport channels. It isfurther contemplated that the combination of channels is based on anoperational state of the mobile terminal.

Preferably, the notification response message is transmitted via acombination of common logical and common transport channels when themobile terminal is in the CELL_PCH state or the URA_PCH state.Preferably, the notification response message is transmitted via acombination of common logical and common transport channels or acombination of dedicated logical and common transport channels when themobile terminal is in the CELL_FACH state. Preferably, the notificationresponse message is transmitted via a combination of common logical andcommon transport channels, a combination of dedicated logical and commontransport channels, or a combination of dedicated logical and dedicatedtransport channels when the mobile terminal is in the CELL_DCH state.

In one embodiment of the invention, a notification response message istransmitted only if a connection for exchanging control data with thenetwork already exists and no connection for exchanging packet-switchedcontrol data with the network exists. If a connection for exchangingpacket-switched control data with the network already exists, no messageis transmitted.

Therefore, only those mobile terminals having no network connection andthose mobile terminals having a network connection but no networkconnection for exchanging packet-switched control data will respond. Thenetwork counts the number of connection request messages andnotification response messages received and utilizes additionalinformation regarding the number of mobile terminals having an existingnetwork connection that is sufficient to receive the service todetermine the appropriate radio bearer to establish.

In another aspect of the present invention, a method is provided forreceiving a multimedia service in a mobile terminal that has joined theservice in a telecommunication system. The method includes receiving aresponse request message from a network and transmitting a notificationresponse message to the network if a connection for exchanging controldata with the network already exists and it is desired to receive theservice. The network utilizes the notification response message whendetermining which radio bearer to set.

When determining whether to transmit a notification response message, amobile terminal is considered to be in an RRC-idle state if noconnection for exchanging control data with the network exists andconsidered to be in an RRC-connected state if a connection forexchanging control data with the network already exists, regardless ofwhether the connection is sufficient to receive packet-switched controldata. Therefore, mobile terminals desiring to receive the service thathave an existing connection to the network will transmit a notificationresponse message. Preferably, the mobile terminal has joined the servicein a mobile telecommunication system.

In another aspect of the present invention, a method is provided forproviding a service to a plurality of mobile terminals having joined theservice in a mobile telecommunication system. The method includestransmitting a response request message to at least one terminal,receiving a least one connection request message or notificationresponse message from a mobile terminal, comparing the sum of the numberof connection request messages received and the number of notificationresponse messages received to a predetermined threshold value, anddetermining a type of radio bearer according to the comparison.

A connection request message is received from a mobile terminal not yethaving a connection for exchanging control data with a core network. Anotification response message is received from a mobile terminal alreadyhaving a connection for exchanging control data with a core network. Itis contemplated that the service may be a point-to-multipoint service.

Preferably, a point-to-point radio bearer is determined if the sum ofthe number of connection request messages received and the number ofnotification response messages received is less than the thresholdvalue. Preferably, a point-to-multipoint radio bearer is determined ifthe sum of the number of connection request messages received and thenumber of notification response messages received is greater than orequal to the threshold value.

It is contemplated that a response request message is transmitted toeach mobile terminal having no connection for exchanging control datawith a core network via a combination of common logical and commontransport channels. It is further contemplated that a response requestmessage is transmitted to each mobile terminal having a connection forexchanging control data with a core network via one of a combinationcommon logical and common transport channels, a combination of dedicatedlogical and common transport channels, and a combination of dedicatedlogical and dedicated transport channels. Moreover, it is contemplatedthat the combination of channels is based on an operational state of themobile terminal to which the response request message is transmitted.

Preferably, the response request message is transmitted via acombination of common logical and common transport channels when themobile terminal is in the CELL_PCH state or the URA_PCH state.Preferably, the response request message is transmitted via acombination of common logical and common transport channels or acombination of dedicated logical and common transport channels when themobile terminal is in the CELL_FACH state. Preferably, the responserequest message is transmitted via a combination of common logical andcommon transport channels, a combination of dedicated logical and commontransport channels, or a combination of dedicated logical and dedicatedtransport channels when the mobile terminal is in the CELL_DCH state.

In another aspect of the present invention, a method is provided forproviding a service to a plurality of mobile terminals having joined theservice in a mobile telecommunication system. The method includesreceiving an indication from a core network of the number of mobileterminals having connections for exchanging packet-switched control datawith the core network, transmitting a response request message to atleast one terminal, receiving at least one connection request message ornotification response message from a mobile terminal, comparing the sumof the number of mobile terminals having connections for exchangingpacket-switched control data with the core network, the number ofconnection request messages received and the number of notificationresponse messages received to a predetermined threshold value, anddetermining a type of radio bearer according to the comparison.

A connection request message is received from a mobile terminal nothaving a connection for exchanging control data with a core network. Anotification response message is received from a mobile terminal havinga connection for exchanging control data with a core network but noconnection for exchanging packet-switched control data. No response isreceived from a mobile terminal having a connection for exchangingpacket-switched control data with a core network. Preferably, theservice is a point-to-multipoint service.

Preferably, a point-to-point radio bearer is determined if the sum ofthe number of mobile terminals having connections for exchangingpacket-switched control data with the core network, the number ofconnection request messages received and the number of notificationresponse messages received is less than the threshold value. Preferably,a point-to-multipoint radio bearer is determined if the sum of thenumber of mobile terminals having connections for exchangingpacket-switched control data with the core network, the number ofconnection request messages received and the number of notificationresponse messages received is greater than or equal to the thresholdvalue.

In another aspect of the present invention, a mobile communicationdevice is provided for receiving a service from a network. The mobilecommunication device includes an RF module, an antenna, a keypad, adisplay, a storage unit, and a processing unit.

The antenna and RF module receive a response request from the networkand transmits a connection response to the network. The keypad allows auser to enter information. The display conveys information to a user.The storage unit stores a connection status for exchanging control datawith the network. The processing unit performs the methods of thepresent invention to process the response request received from thenetwork and generates the connection response based on the connectionstatus.

The connection response includes a connection request message if theconnection status indicates no connection for exchanging control datawith the network exists. In one embodiment, the connection responseincludes a notification response message if the connection statusindicates a connection for exchanging control data with the networkalready exists. In another embodiment, the connection response includesa notification response message only if the connection status indicatesa connection for exchanging control data with the network already existsand no connection for exchanging packet-switched control data with thenetwork exists and no connection response is transmitted if theconnection status indicates a connection for exchanging packet-switchedcontrol data with the network already exists.

In another aspect of the present invention, a network is provided forproviding a service to a plurality of mobile terminals having joined theservice in a mobile telecommunication system. The network includes atransmitter, a receiver and a controller.

The transmitter transmits a response request message to at least onemobile terminal. The receiver receives at least one connection requestmessage or notification response message from a mobile terminal.

In one embodiment, the controller performs the methods of the presentinvention to compare the sum of the number of connection requestmessages received and the number of notification response messagesreceived to a predetermined threshold value in order to determine a typeof radio bearer according to the comparison. In another embodiment, thecontroller performs the methods of the present invention to receive anindication from a core network of the number of mobile terminals havingconnections for exchanging packet-switched control data with the corenetwork and compare the sum of the number of mobile terminals havingconnections for exchanging packet-switched control data with the corenetwork, the number of connection request messages received and thenumber of notification response messages received to a predeterminedthreshold value in order to determine a type of radio bearer accordingto the comparison.

It is to be understood that both the foregoing explanation and thefollowing detailed description of the present invention are exemplaryand illustrative and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a block diagram of a conventional UMTS networkstructure.

FIG. 2 illustrates a diagram of a connection of a plurality of UEs to acore network providing an MBMS according to a conventional method.

FIG. 3 illustrates a diagram of the RRC state transition of a mobileterminal.

FIG. 4 illustrates a diagram of a connection of a plurality of UEs to acore network providing an MBMS according to a first embodiment of thepresent invention.

FIG. 5 illustrates a diagram of a connection of a plurality of UEs to acore network providing an MBMS according to a second embodiment of thepresent invention.

FIG. 6 illustrates a mobile communication device for receiving a servicefrom a network according to one embodiment of the present invention.

FIG. 7 illustrates a network for transmitting a service to a mobileterminal according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a method and apparatus for selecting aradio bearer type for providing a service to a plurality of mobileterminals according to a count of mobile terminals obtained throughresponses to a service response request message from a network, thecount including network-connected mobile terminals that still need toestablish a connection in order to receive the service. Although thepresent invention is illustrated with respect to a mobile terminal, itis contemplated that the present invention may be utilized anytime it isdesired to select a radio bearer type for providing a service to aplurality of mobile communication devices by performing a countingoperation that includes those devices that have an existing connectionto a network.

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Throughout the drawings, like elements are indicated using thesame or similar reference designations.

Upon receiving a “session start” message from a core network 4 for aspecific service, for example an MBMS, an RNC 10 transmits a servicenotification, for example an MBMS notification, to mobile terminals 2,for example UEs, in a cell desiring to receive the service. According tothe present invention, an MBMS response request message is transmittedtogether with the MBMS notification and includes a service ID enablingthe receiving UE 2 to ascertain to which MBMS the response requestmessage corresponds.

The MBMS response request message is transmitted to UEs 2 in theRRC-connected mode as well as to those in the RRC-idle mode. Acombination of common logical and transport channels is used to transmitthe MBMS response request message to RRC-idle UEs 2. Additionally, acombination of dedicated logical and common transport channels anddedicated logical and dedicated transport channels is used to transmitthe MBMS response request message to RRC-connected UEs 2. Thetransmission of the MBMS response request message to the RRC-connectedUEs 2 may use the same common logical and transport channels used fortransmission to the RRC-idle UEs or may use another combination of thesechannels.

The combination of channels is based on an operational state of the UE 2to which the transmission is made and the available channel differsaccording to the operational state. The possible logical channelsinclude control channels BCCH, PCCH, CCCH, and DCCH, and trafficchannels DTCH and CTCH. The possible transport channels include thecommon transport channels BCH, PCH, RACH, FACH, CPCH, and DSCH and thededicated transport channel DCH.

FIG. 3 illustrates operational transitions of a UE 2, between theRRC-idle mode and the RRC-connected mode. Four operational states of aUE 2 in the RRC-connected mode are illustrated, specifically theCell_DCH state, the Cell_FACH state, the Cell_PCH state, and the URA_PCHstate. In FIG. 3, curved arrows indicate potential transitions betweenstates.

In the Cell_DCH state, the UE 2 transmits and receives data via adedicated transport channel, for example DCH, using dedicated logicalchannels, for example DCCH and DTCH, to receive high-capacity PSservices and most CS services. Transition to the Cell_DCH state occurswhen a UE 2 in the RRC-idle mode establishes an RRC connection or when adedicated transport channel is allocated to a UE in the Cell_FACH state.The UE 2 receiving an MBMS in the Cell_DCH state can make a transitionto the Cell_FACH state if the data volume decreases and may transitionto the Cell_PCH or URA_PCH state to reduce power consumption in theevent of an extended absence of data transfer. An RRC-connected UE 2transitions to the RRC-idle mode when there is no further service to beprovided.

In the Cell_FACH state, the UE 2 transmits and receives data via commontransport channels, for example RACH and FACH, using dedicated logicalchannels, for example DCCH and DTCH, and common logical channels, forexample CCCH and CTCH, to receive low-capacity PS services. Transitionto the Cell_FACH state takes place if a UE 2 in the RRC-idle modeestablishes an RRC connection, if an RRC-connected UE in the Cell_DCHstate needs to switch to a common transport channel due to a reductionin data volume, or if a UE in the Cell_PCH or URA_PCH state needs totransmit or receive data. The UE 2 receiving an MBMS in the Cell_FACHstate may make a transition to the Cell_DCH state if the data volumeincreases and may transition to the Cell_PCH or URA_PCH state to reducepower consumption in the event of an extended absence of data transfer.

While in the Cell_PCH or URA_PCH state, the UE 2 receives a pagingchannel, for example PCH, among dedicated channels while performing adiscontinuous reception (DRX) function to reduce power consumption,whereby a logical channel, for example PCCH, among common logicalchannels is receivable. These states are mainly used for the bursty dataof a PS service.

The same basic operation of standing by to receive the paging channel,for example PCH, is applicable to both the Cell_PCH and URA_PCH states.The Cell_PCH and URA_PCH states differ from each other, however, interms of their update cycles.

A UE 2 in the Cell_PCH state keeps looking for a better cell.Particularly applicable when the UE 2 is traveling at high speed, the UEperforms a cell update by UTRAN registration areas (URAs). URAs are areaunits much larger than one cell. Transition to the Cell_PCH or URA_PCHstate occurs if data transfer of a Cell_FACH or Cell_DCH UE 2 istemporarily interrupted. When data transfer restarts, the UE 2 makes atransition to the Cell_FACH or Cell_DCH state according to data volume.

According to the channel combinations illustrated in FIG. 3, the MBMSresponse request message from the RNC 10 may be received by anRRC-connected mode UE 2 regardless of its operational state. Preferably,the transmission of the MBMS response request message uses a combinationof common logical or transport channels for UEs 10 in the Cell_PCH orURA_PCH state. Preferably, the transmission of the MBMS response requestmessage uses a combination of common logical or transport channels or acombination of dedicated logical channels or common transport channelsfor UEs 2 in the Cell_FACH state. Preferably, the transmission of theMBMS response request message uses a combination of common logical ortransport channels, a combination of dedicated logical channels orcommon transport channels, or a combination of dedicated logicalchannels or dedicated transport channels for UEs 2 in the Cell_DCHstate. If two or more such channel combinations are possible, as in thecase of the Cell_FACH or Cell_DCH state, the MBMS response requestmessage to an RRC-connected UE 2 may be transmitted via the same channelcombinations.

According to the present invention, an RRC-connected UE 2, having joinedan MBMS, receives an MBMS response request message from the RNC 10 andresponds by transmitting a notification response message to the RNC. Thenotification response can be selectively transmitted.

For example, the UE 2 may check to determine whether the MBMS isreceivable and transmit a notification response message accordingly. Onthe other hand, the user may arbitrarily determine whether anotification response message is transmitted and whether thenotification response message is transmitted immediately or after theRNC 10 determines the radio bearer type, in which case the notificationresponse message would be transmitted only in the event of apoint-to-point radio bearer.

The notification response message includes MBMS ID information enablingthe RNC 10 to ascertain to which MBMS the notification response messagecorresponds and includes RNC ID information enabling the RNC toascertain which UE 2 transmitted the notification response message. TheRNC 10 allocates RNC ID information for RRC-connected UEs 2 only. TheRNC ID information, which enables the RNC 10 to identify each UE 2, isbased on a UE's radio network temporary identifier (RNTI) and uses thecell RNTI to identify the UE by cell or the UTRAN RNTI to identify theUE by RNC.

A UE 2 in RRC-connected mode transmits the notification responsemessage-using channel combinations determined according to itsoperational state. Preferably, the notification response message istransmitted using a combination of common logical and transport channelsfor UEs 2 in the Cell_PCH or URA_PCH state. Preferably, the notificationresponse message is transmitted using a combination of common logicaland transport channels or a combination of dedicated logical channelsand common transport channels for UEs 2 in the Cell_FACH state.Preferably, the notification response message is transmitted using acombination of common logical and transport channels, a combination ofdedicated logical channels and common transport channels, or acombination of dedicated logical channels and dedicated transportchannels for UEs 2 in the Cell_DCH state. If two or more such channelcombinations are possible, as in the case of the Cell_FACH or Cell_DCHstate, the notification response message from an RRC-connected UE 2 maybe transmitted via the same channel combinations.

For each session of a specific MBMS, the RNC 10 adds the number ofnotification response messages received from RRC-connected UEs 2 to thenumber of RRC connection request messages received from RRC-idle UEs andutilizes the total and a threshold to establish an MBMS radio bearer.

FIG. 4 illustrates a connection of a plurality of UEs 2 to a corenetwork 4 providing an MBMS according to a first embodiment of theinvention. The RNC 10 counts RRC-connected UEs 2 joining the MBMS. Asindicated by the dotted lines in FIG. 4, a UE 2 in the RRC-connectedmode may have a connection between either the MSC 14 and/or the SGSN 18or neither one. If the UE 2 transmits a notification response messageusing a combination of dedicated logical channels and dedicatedtransport channels, the RNC ID can be omitted since the RNC 10 mayidentify the UE from which the message is transmitted.

The method of the first embodiment illustrated in FIG. 4 counts UEs 2 inthe RRC-connected mode for a specific MBMS according to notificationresponse messages received regardless of whether the RRC-connected UEsalso have a connection with the SGSN 18, that is regardless of whetherthe UEs are PMM-connected or PMM-idle. Since the RNC 10 counts thenumber of UEs 2 having a PS connection, or those that are PMM-connected,among a plurality of RRC-connected UEs, radio resources may be wasted byunnecessary transmissions of the MBMS response request and notificationresponse messages. To conserve radio resources, the method illustratedin FIG. 5 is proposed.

FIG. 5 illustrates a connection of a plurality of UEs 2 to a corenetwork 4 providing an MBMS according to a second embodiment of theinvention. The RNC 10 utilizes a method similar to that illustrated inFIG. 2 to count the number of UEs 2 in either the RRC-idle mode or boththe RRC-connected and PMM-connected mode. The RNC 10 utilizes a methodsimilar to that illustrated in FIG. 4 to count the number of UEs 2 inthe RRC-connected and PMM-idle mode.

The number of RRC connection request messages received determines thenumber of RRC-idle UEs 2. The number of UEs 2 in both the RRC-connectedmode and PMM-connected mode is determined from information received fromthe SGSN 18. An MBMS response request message and notification responsemessages are utilized to count the number of UEs in the RRC-connectedand PMM-idle mode.

As indicated by the dotted lines in FIG. 5, a UE2 in the RRC-connectedand PMM-idle mode may or may not have a CS connection. The secondembodiment of the invention differs from the first embodiment of theinvention in that UEs 2 in the RRC-connected mode, having received theMBMS response request message, transmits a notification response messageonly if the UE is also in the PMM-idle mode. By preventing a UE in boththe RRC-connected and PMM-connected mode from unnecessarily transmittinga notification response message, radio resources may be conserved.

Referring to FIG. 6, a block diagram of a mobile communication device100 of the present invention is illustrated, for example a mobile phonefor performing the methods of the present invention. The mobilecommunication device 100 includes a processing unit 110 such as amicroprocessor or digital signal processor, an RF module 135, a powermanagement module 105, an antenna 140, a battery 155, a display 115, akeypad 120, a storage unit 130 such as flash memory, ROM or SRAM, aspeaker 145 and a microphone 150.

A user enters instructional information, such as a telephone number, forexample, by pushing the buttons of the keypad 120 or by voice activationusing the microphone 150. The processing unit 110 receives and processesthe instructional information to perform the appropriate function, suchas to dial the telephone number. Operational data may be retrieved fromthe memory unit 130 to perform the function. Furthermore, the processingunit 110 may display the instructional and operational information onthe display 115 for the user's reference and convenience.

The processing unit 110 issues instructional information to the RFmodule 135, to initiate communication, for example, by transmittingradio signals comprising voice communication data. The RF module 135includes a receiver and a transmitter to receive and transmit radiosignals. The antenna 140 facilitates the transmission and reception ofradio signals. Upon receiving radio signals, the RF module 135 mayforward and convert the signals to baseband frequency for processing bythe processing unit 110. The processed signals may be transformed intoaudible or readable information output, for example, via the speaker145.

The RF module 135 is adapted to receive a response request from anetwork 4 and to transmit a connection response to the network and thestorage unit 130 is adapted to store a connection status for exchangingcontrol data with the network. In one embodiment, the processing unit110 is adapted to process the response request and generate theconnection response based on the connection status such the connectionresponse includes a connection request message if the connection statusindicates that the mobile terminal has no connection for exchangingcontrol data with the network and the connection response includes anotification response message if the connection status indicates thatthe mobile terminal has a connection for exchanging control data withthe network. In another embodiment, the processing unit 110 is adaptedto generate a connection response including a notification responsemessage only if the connection status indicates that the mobile terminalhas a connection for exchanging control data with the network and has noconnection for exchanging packet-switched control data with the networkand to generate no connection response if the connection statusindicates the mobile terminal has a connection for exchangingpacket-switched control data with the network.

FIG. 7 illustrates a block diagram of a UTRAN 220 according to oneembodiment of the present invention. The UTRAN 220 includes one or moreradio network sub-systems (RNS) 225. Each RNS 225 includes a radionetwork controller (RNC) 223 and a plurality of Node-Bs 221, or basestations, managed by the RNC. The RNC 223 handles the assignment andmanagement of radio resources and operates as an access point withrespect to the core network 4. Furthermore, the RNC 223 is adapted toperform the methods of the present invention.

The Node-Bs 221 receive information sent by the physical layer of theterminal 110 through an uplink and transmit data to the terminal througha downlink. The Node-Bs 221 operate as access points, or as atransmitter and receiver, of the UTRAN 220 for a mobile terminal 100.

The Node-Bs 221 are adapted to transmit a response request message to atleast one mobile terminal 100 and to receive at least one connectionrequest message or notification response message from at least onemobile terminal. In one embodiment, the RNC 223 is adapted to comparethe sum of the number of connection request messages received and thenumber of notification response messages received to a predeterminedthreshold value in order to determine a type of radio bearer accordingto the comparison. In another embodiment, the RNC 223 is adapted toreceive an indication from a core network 4 of the number of mobileterminals 100 having connections for exchanging packet-switched controldata with the core network and compare the sum of the number of mobileterminals having connections for exchanging packet-switched control datawith the core network, the number of connection request messagesreceived and the number of notification response messages received to apredetermined threshold value to determine a type of radio beareraccording to the comparison.

An RNC and network adopting the methods of the present invention cancorrectly count the number of UEs for a specific MBMS to select anappropriate MBMS radio bearer, thereby enabling increased radio resourceefficiency. The present invention ensures that a UE joining an MBMS canbe provided the service in all situations. In particular, the methods ofthe present invention enable the counting of RRC-connected UEs having noPS connection, which cannot be counted by the conventional method whenthe UTRAN counts UEs intending to receive an MBMS.

It will be apparent to one skilled in the art that the preferredembodiments of the present invention can be readily implemented using,for example, the processor 110 or other data or digital processingdevice, either alone or in combination with external support logic.

Although the present invention is described in the context of mobilecommunication, the present invention may also be used in any wirelesscommunication systems using mobile devices, such as PDAs and laptopcomputers equipped with wireless communication capabilities. Moreover,the use of certain terms to describe the present invention should notlimit the scope of the present invention to certain type of wirelesscommunication system, such as UMTS. The present invention is alsoapplicable to other wireless communication systems using different airinterfaces and/or physical layers, for example, TDMA, CDMA, FDMA, WCDMA,etc.

The preferred embodiments may be implemented as a method, apparatus orarticle of manufacture using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. The term “article of manufacture” as used herein refers to codeor logic implemented in hardware logic (e.g., an integrated circuitchip, Field Programmable Gate Array (FPGA), Application SpecificIntegrated Circuit (ASIC), etc.) or a computer readable medium (e.g.,magnetic storage medium (e.g., hard disk drives, floppy disks, tape,etc.), optical storage (CD-ROMs, optical disks, etc.), volatile andnon-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs,SRAMs, firmware, programmable logic, etc.).

Code in the computer readable medium is accessed and executed by aprocessor. The code in which preferred embodiments are implemented mayfurther be accessible through a transmission media or from a file serverover a network. In such cases, the article of manufacture in which thecode is implemented may comprise a transmission media, such as a networktransmission line, wireless transmission media, signals propagatingthrough space, radio waves, infrared signals, etc. Of course, thoseskilled in the art will recognize that many modifications may be made tothis configuration without departing from the scope of the presentinvention, and that the article of manufacture may comprise anyinformation bearing medium known in the art. The logic implementationshown in the figures described specific operations as occurring in aparticular order. In alternative implementations, certain of the logicoperations may be performed in a different order, modified or removedand still implement preferred embodiments of the present invention.Moreover, steps may be added to the above described logic and stillconform to implementations of the invention.

What is claimed is:
 1. A method of transmitting a message from a mobileterminal which desires to receive a multimedia broadcast multicastservice (MBMS) to a network in a mobile telecommunication system, themethod comprising: receiving an MBMS notification from the network, theMBMS notification associated with the multimedia broadcast multicastservice (MBMS); and transmitting a message to the network afterreceiving the MBMS notification, if the mobile terminal is in anRRC-connected (Radio Resource Control-connected) and PMM-idle (PacketMobility Management-idle) mode in which the mobile terminal has aconnection for exchanging control data with the network but no packetswitching (PS) connection with a core network.
 2. The method of claim 1,wherein the MBMS notification is received via one of a combinationcommon logical and common transport channels, a combination of dedicatedlogical and common transport channels, and a combination of dedicatedlogical and dedicated transport channels.
 3. The method of claim 1,wherein the MBMS notification is received via a combination of commonlogical and common transport channels when the mobile terminal is in theCELL_PCH state.
 4. The method of claim 1, wherein the MBMS notificationis received via a combination of common logical and common transportchannels when the mobile terminal is in the URA_PCH state.
 5. The methodof claim 1, wherein the MBMS notification is received via one of acombination of common logical and common transport channels and acombination of dedicated logical and common transport channels when themobile terminal is in the CELL_FACH state.
 6. The method of claim 1,wherein the MBMS notification is received via one of a combination ofcommon logical and common transport channels, a combination of dedicatedlogical and common transport channels, and a combination of dedicatedlogical and dedicated transport channels when the mobile terminal is inthe CELL_DCH state.
 7. The method of claim 1, wherein the message istransmitted via a combination of common logical and common transportchannels when the mobile terminal is in a CELL_PCH state.
 8. The methodof claim 1, wherein the message is transmitted via a combination ofcommon logical and common transport channels when the mobile terminal isin the URA_PCH state.
 9. The method of claim 1, wherein the message istransmitted via one of a combination of common logical and commontransport channels and a combination of dedicated logical and commontransport channels when the mobile terminal is in a CELL_FACH state. 10.The method of claim 1, wherein the message is transmitted via one of acombination common logical and common transport channels, a combinationof dedicated logical and common transport channels, and a combination ofdedicated logical and dedicated transport channels when the mobileterminal is in the CELL_DCH state.
 11. The method of claim 1, furthercomprising performing transition of state of the mobile terminal fromthe PMM-idle mode to a PMM-connected mode after transmitting themessage.
 12. A method of exchanging messages with a plurality of mobileterminals which desire to receive a multimedia broadcast multicastservice (MBMS) in a network of a mobile telecommunication system, themethod comprising: transmitting a MBMS notification to at least one ofthe plurality of mobile terminals; and receiving at least one messagefrom the at least one of the plurality of mobile terminals aftertransmitting the MBMS notification, if the at least one of the pluralityof mobile terminals is in an RRC-connected (Radio ResourceControl-connected) and PMM-idle (Packet Mobility Management-idle) modein which the at least one of the plurality of mobile terminals has aconnection for exchanging control data with the network but no packetswitching (PS) connection with a core network.
 13. The method of claim12, wherein the MBMS notification is transmitted to each of theplurality of mobile terminals having no connection for exchangingcontrol data with a core network via a combination of common logical andcommon transport channels.
 14. The method of claim 12, wherein the MBMSnotification is transmitted to each of the plurality of mobile terminalshaving a connection for exchanging control data with a core network viaone of a combination common logical and common transport channels, acombination of dedicated logical and common transport channels, and acombination of dedicated logical and dedicated transport channels. 15.The method of claim 12, wherein the MBMS notification is transmitted viaa combination of common logical and common transport channels when themobile terminal is in one of the CELL_PCH state and URA_PCH state. 16.The method of claim 12, wherein the MBMS notification is transmitted viaone of a combination of common logical and common transport channels anda combination of dedicated logical and common transport channels whenthe mobile terminal is in the CELL_FACH state.
 17. The method of claim12, wherein the MBMS notification is transmitted via one of acombination common logical and common transport channels, a combinationof dedicated logical and common transport channels, and a combination ofdedicated logical and dedicated transport channels when the mobileterminal is in the CELL_DCH state.
 18. The method of claim 12, whereinthe at least one message is received via a combination of common logicaland common transport channels when the mobile terminal is in a CELL_PCHstate.
 19. The method of claim 12, wherein the at least one message isreceived via a combination of common logical and common transportchannels when the mobile terminal is in the URA_PCH state.
 20. Themethod of claim 12, wherein the at least one message is received via oneof a combination common logical and common transport channels, acombination of dedicated logical and common transport channels, and acombination of dedicated logical and dedicated transport channels whenthe mobile terminal is in the CELL_DCH state.